Ultrahard materials such as polycrystalline diamond (PCD) and polycrystalline cubic boron nitride (PcBN) are known in the art. Conventional PCD is formed from combining diamond grains or crystals with a binder/catalyst material and processing the same at high pressure/high temperature (HP/HT) conditions. Such ultrahard materials have well known properties of wear resistance that make them a popular material choice for use in certain industrial applications, such as cutting tools for machining and subterranean mining and drilling bits where wear resistance is highly desired. For example, conventional PCD can be used to form wear or cutting surfaces of cutting elements used with fixed body and rotary cone subterranean drilling bits to impart an improved degree of improved wear resistance thereto.
Conventional PCD has a material microstructure characterized by a plurality of bonded together diamond grains, forming an intercrystalline bonded diamond phase, and a plurality of interstitial regions interposed between the diamond grains that contain the binder/catalyst material used to catalyze the bonding of the diamond grains. While this material microstructure provides known properties of improved wear resistance when compared to other non-PCD materials, it is also known to be relatively brittle, thus limiting practical use of such convention PCD to those applications calling for an improved degree of wear resistance but not requiring a high degree of toughness.
However, because many industrial wear and cutting applications require an improved degree of both wear resistance and toughness, attempts were made in the art to address this need by either varying the content of the diamond grain and binder/catalyst material used to form the PCD, and/or by varying the size or grade of the diamond grains used to form the PCD. While these approaches did achieve some improvement in the toughness of the PCD, they did so at the expense or sacrifice or wear resistance.
Further attempts were made to produce a PCD material having the desired improvements in toughness, but without sacrificing wear resistance. One such attempt focused on developing a two-phase composite construction having a material microstructure comprising an arrangement of PCD material phases dispersed within a ductile binder material matrix phase. In this construction, the PCD material phases operated to impart a desired level of wear resistance while the ductile binder matrix phase operated to impart a desired degree of toughness to the resulting composite construction. While this approach was successful in reducing the amount of wear resistance sacrificed while improving the degree of toughness for a PCD-containing material when compared to the prior attempts made with monolithic PCD materials, a desired degree or level of both properties was still not achieved as needed to meet certain demanding end use applications.
Such prior art attempts of developing PCD materials suitable for use in wear and/or cutting applications calling for heightened degrees of both wear resistance and toughness have all approached such need from the perspective of increasing the toughness of inherently brittle PCD materials.
Additionally, in each of the above-described prior art approaches, the PCD material or PCD phase of the composite construction, was formed in the manner noted above. Namely, by starting with combining diamond grains with a binder/catalyst material as the starting feedstock and then subjecting the same to HP/HT processing. In the above-noted PCD composite construction, the PCD material phase was formed by combining diamond grains with the binder/catalyst material and a suitable processing agent for forming a green-state particle, and then dispersing the particles into a further ductile binder material. Accordingly, in each instance the PCD material or composite construction phase was formed by starting with diamond grains as the feedstock material.
Currently, a need exists to facilitate and expedite the process of forming ultrahard material constructions. Further, it has been discovered that for certain ultrahard materials already known to have a desired degree of toughness, a need exists for improving the wear resistance of these materials to make them better suited for applications calling for heightened levels of both toughness and wear resistance.
It is, therefore, desired that ultrahard material constructions be developed that have desired properties of both toughness and wear resistance, making them suitable for use in demanding industrial wear and/or cutting applications that require heightened levels of both wear resistance and toughness not otherwise obtainable from conventional monolithic PCD materials or known PCD composite constructions. It is also desired that a constituent useful for forming such ultrahard material constructions, and a method for making the constituent and the ultrahard material constructions, be developed for the purpose of facilitating the process of preparing such ultrahard material constructions.